1. Field of the Invention
The present invention relates to the field of electricity meter covers, and, more particularly, to an integrally molded electricity meter cover including a reset arrangement.
2. Prior Art
A typical electronic watthour meter for measuring electric energy consumption requires resetting of the demand function after periodic reading of the meter, such as every month. The reset is typically accomplished by activating a reset switch located somewhere on the meter itself and under the cover. Generally the reset switch (or button) is actuated by depressing a plunger positioned in proximity to the button and extending through the cover. For example, an early prototype version of the General Electric EVX meter produced by the assignee of the present invention, included a plunger carried by the housing. The plunger, once rotated 90.degree. to an activate position, could be depressed by the technician or meter reader to activate the reset switch positioned inside the meter cover to thereby reset the meter.
Tampering with the reset plunger is typically discouraged by the provision of a switch cover or latch cover for the plunger. The switch cover is typically pivotally connected to the meter housing and is movable between open and closed positions. In the open position, the plunger may be rotated and depressed to reset the meter. In the closed position, activation of the plunger is not possible, since the plunger cannot be rotated or depressed. Moreover, the switch cover typically allows for a wire, band or padlock seal to be used to secure the switch cover in the closed position.
The early prototype EVX meter, for example, included a plunger having a thumbgrip portion which permitted the technician to grasp and then rotate the plunger. The thumbgrip portion included a circular opening in communication with a slotted opening thereby permitting insertion of either a padlock or tape seal. The latch cover of this early prototype meter had a rectangular cutout roughly aligned with the openings in the plunger. Accordingly, a seal or padlock would retain the latch cover in the closed position and prevent operation of the plunger. Unfortunately, the padlock or seal of the early EVX meter was supported only by the thumbgrip portion of the plunger. Accordingly, the plunger could be damaged by manipulation of the seal or padlock thereby requiring replacement of the plunger.
The switch cover of the early EVX meter was snapped in place on a hinge pin integrally molded into the housing or meter cover. In addition, an external bump was molded on an outer portion of the switch cover to attempt to provide means for holding the latch cover in the open position when the plunger was accessed by a technician. The convenience of the technician is enhanced if the cover may be secured in the open position. Unfortunately, the early EVX meter cover latch did not provide the desired positive locking in the open position. Moreover, the typical plastic materials used for a meter housing and for the associated switch cover and hinge pin may be susceptible to both molded-in stresses and stresses produced during operation. These stresses are amplified particularly in the presence of notches, nicks, cuts, etc. Environmental influences may also degrade the typical polycarbonate plastic material and may lead to a failure of the switch cover to remain in the open position.
Another disadvantage of the early EVX meter resulted from the hinge portion of the switch cover defining an exposed opening for moisture and dirt to enter into the area between the hinge pin and hinge portion. Accordingly, the long term reliability of the hinge may suffer.
Another prior art arrangement includes a housing, a switch means positioned within an opening in said housing, a hinge pin connected to the meter housing and a switch means cover pivotally connected to the hinge pin and adapted to prevent actuation of the switch means when closed and to permit such actuation when open. While the apparatus is well suited to its intended purpose, it does require two operations to reset the meter, i.e., opening of the switch cover and rotating of the switch means before that means is appropriately configured to be used to reset the meter. Moreover, the unit requires considerable assembly time translating to costly manufacture.
Other prior art arrangements have included a number of parts associated with the reset mechanism. For example, one arrangement utilizes six parts for the reset alone: the hasp is ultrasonically welded onto the cover and the mechanism further includes a latch, a pin, a shaft, a plunger and a gasket. As can easily be appreciated, the number of parts creates cost. In yet another arrangement a machined hasp is attached by threads, gaskets, a pair of flat washers, a lockwasher and a nut, and this is only for the hasp. To complete the reset arrangement, a latch and plunger including a metal latch, a pin, a plunger, a a washer, a at least one gasket and a screw to hold the plunger on the rest of the arrangement. Clearly a formidable number of parts for a relatively simple operation. Still another prior art arrangement comprises a welded on hasp (in fact a two piece structure itself) and a preassembled plunger having a metal latch, a spring to hold the latch up and a separate piece to hold the latch again to many pieces and therefore less desirable than the present invention as discussed hereinbelow.